.TH std::isxdigit(std::locale) 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::isxdigit(std::locale) \- std::isxdigit(std::locale)

.SH Synopsis
   Defined in header <locale>
   template< class CharT >
   bool isxdigit( CharT ch, const locale& loc );

   Checks if the given character is classified as a hexadecimal digit by the given
   locale's std::ctype facet.

.SH Parameters

   ch  - character
   loc - locale

.SH Return value

   Returns true if the character is classified as a hexadecimal digit, false otherwise.

.SH Possible implementation

   template<class CharT>
   bool isxdigit(CharT ch, const std::locale& loc)
   {
       return std::use_facet<std::ctype<CharT>>(loc).is(std::ctype_base::xdigit, ch);
   }

.SH Example


// Run this code

 #include <iostream>
 #include <locale>
 #include <string>
 #include <unordered_set>

 struct gxdigit_ctype : std::ctype<wchar_t>
 {
     std::unordered_set<wchar_t> greek_digits{L'α', L'β', L'γ', L'δ', L'ε', L'ζ'};

     bool do_is(mask m, char_type c) const override
     {
         return (m & xdigit) && greek_digits.contains(c)
             ? true // 6 first Greek small letters will be classified as digits
             : ctype::do_is(m, c); // leave the rest to the parent class
     }
 };

 int main()
 {
     std::wstring text = L"0123456789abcdefABCDEFαβγδεζηθικλμ";
     std::locale loc(std::locale(""), new gxdigit_ctype);

     std::locale::global(std::locale("en_US.utf8"));
     std::wcout.imbue(std::locale());

     std::wcout << "Hexadecimal digits in text: ";
     for (const wchar_t c : text)
         if (std::isxdigit(c, loc))
             std::wcout << c << L' ';
     std::wcout << L'\\n';

     std::wcout << "Not hexadecimal digits in text: ";
     for (const wchar_t c : text)
         if (not std::isxdigit(c, loc))
             std::wcout << c << L' ';
     std::wcout << L'\\n';
 }

.SH Output:

 Hexadecimal digits in text: 0 1 2 3 4 5 6 7 8 9 a b c d e f A B C D E F α β γ δ ε ζ
 Not hexadecimal digits in text: η θ ι κ λ μ

.SH See also

   isxdigit  checks if a character is a hexadecimal character
             \fI(function)\fP
   iswxdigit checks if a wide character is a hexadecimal character
             \fI(function)\fP
